Coronary artery bypass grafting surgeries are very challenging procedures that require suturing of tiny vessels (with diameters as small as 1.5 mm) on the surface of the heart. Presently the common practice is to stop the heart while such suturing takes place and bypass the natural blood oxygenation process through the lungs with an artificial cardiopulmonary bypass machine.
Because the disadvantages of cardio-pulmonary bypass are numerous and have been well documented in the literature (Kirkland, 1993; The Committee on Trauma, 1996), several approaches have been proposed to perform coronary artery bypass grafting surgery without stopping the heart. All such approaches require the stabilization of the cardiac tissue surrounding the coronary bypass site without significant bleeding to allow the above-mentioned delicate suturing to take place. Several approaches have been proposed to accomplish a stable operating field.
In one common approach, tissue surrounding the coronary is sutured to a fixed support, allowing the grafting surgery to proceed. The fixation suturing is time consuming and relies on significant tissue stretching to achieve a reasonably stable surgical field. Significant tissue motion is still present, implying that the quality of the grafts is not as high as it could be.
In another common approach, cardiac tissue stabilizers that press down on the coronary artery bypass site have been proposed. CTS (Cremer et al., 1997; Boonstra et al., 1997) and Guidant (Guidant Corporation, 1997) Corporations make devices that rely on a horseshoe shaped mechanism to push down the region of the coronary artery requiring bypass, trapping the heart tissue at this location. The CTS horseshoe (Cremer et al., 1997; Boonstra et al., 1997) is attached to a vertical rod which is screw-tightened to a slide which is screwmounted to a custom made chest retractor. This gives it three degrees of freedom. The Guidant device's horseshoe is fixated to the chest retractor through a flexible cable clamp mechanism screw also tightened to the retractor. The push-down mechanisms developed have to press on the heart with sufficient force to still be in contact with the cardiac tissue when the heart is fully contracted.
Another approach proposed in Borst et al., 1996, consists of using discrete suction cups around the coronary bypass site to fixate tissue with respect to the retractor or an adjustable surgical stand. In one of the embodiments of this approach, several sets of discrete suction cups are held on rods mounted on cable clamps, resembling an "Octopus" latching on tissue surrounding the surgical sight. In turn, the cable clamps are screw-fastened to an adjustable surgical stand or fastened to a support attached to the operating table. The art taught in Borst, 1996, has led to a product marketed by Medtronic called the "Octopus" device (Medtronic, 1997).
U.S. Pat. No. 5,727,569, Benetti et al., Mar. 17, 1998, discloses devices and techniques which use a negative (suction) pressure or vacuum, applied through a surgical instrument, to fix the position of a portion of the surface of a beating heart so that a surgical procedure can be more easily performed. The devices apply a negative pressure at several points on the outer surface of the heart such that a portion of the heart is fixed in place by the suction imposed through the surgical instrument. Because the instrument fixes the position of the tissue, and because the instruments remain at a constant distance from the particular portion of the heart where the surgery is being performed, the device may also serve as a support or platform so that other surgical instruments or devices can be advantageously used at the site. In certain perferred embodiments, the devices described herein have structures to facilitate the use of additional surgical instruments such that the placement of negative pressure device permits the surgeon to advantageously manipulate the other instruments during surgery. The negative pressure is preferably imposed through a plurality of ports which may be disposed in a substantially planar surface of the instrument which contacts the cardiac tissue.
WO 98/37814, Takahashi, published Sep. 3, 1998, discloses an improved device to hold an anastomotic site of coronary artery for the bypass surgery; to provide said device wherein the coronary artery bypass operation can be quickly and accurately performed on the beating heart by firmly and atraumatically holding said anastomotic site motionless and bloodless. That is to say, the characteristic feature of the present invention is in that the coronary artery can be stably held motionless without need to forcedly compress the heart surface. This is accomplished with a circular flexible suction device which surrounds the target artery, and whose center is open to expose the anastomotic site. The device is suctioned to the heart surface by drawing off the air in the flexible circular channel, creating negative pressure.
U.S. Pat. No. 5,749,892, Vierra, May 12, 1998, discloses a system and method for performing less invasive surgical procedures within a body cavity. In a preferred embodiment, the invention provides a system and method for isolating a surgical site such as an anastomosis between an internal mammary artery and a coronary artery in a thoracoscopic coronary artery bypass grafting procedure. The system comprises a foot pivotally coupled to the distal end of a shaft by a linkage. The foot has first and second engaging portions with contact surfaces for engaging a tissue surface. The engaging portions are movable between an open position, where the contact surfaces are separated by a gap, and a collapsed position, where the foot is configured for delivery through the percutaneous penetration. An actuator, at the proximal end of the shaft, can be rotated to pivot the foot about a transverse axis to that the contact surfaces are oriented generally parallel to the surgical site to apply pressure to the tissue structure on both side of the surgical site.
A number of surgical arms have been developed in the past for holding, positioning and supporting patient limbs during operation (Auchinleck et al., 1992; McEwen et al., 1993; McEwen et al., 1993).
U.S. Pat. No. 4,616,632, Wigoda, Oct. 14, 1986, discloses a set of retractors which are coupled by releasable locks to rods on the side of an operating table. A foot pedal is provided to release the locks and allow the retractors to be repositioned easily and with one hand by the doctor while performing the surgery. The foot pedal may utilize hydraulic fluid to lock or release the movement of the retractors. The joint holding the retractors is also rendered free to rotate to properly position the retractors, when the foot pedal is depressed.
U.S. Pat. No. 4,863,133, Bonnell, Sep. 5, 1989, discloses an instrument-supporting, articulated device with a distal end capable of supporting an instrument in the region of a surgical operating site. The device has at least one joint that supports a movable distal support element relative to a proximal support, the joint being associated with a mode selector. The joint has structure capable, upon selection of a first mode of operation by the selector, of enabling relatively free motion of the joint for achieving a desired positon of the instrument and the joint has structure capable, upon selection of a second mode of operation by the selector, to set the position of the instrument in space with lightly loaded restraint. The lightly loaded restraint is of a value that, while the second mode continues to be selected, the user may adjust the position of the instrument by application of a light force to the instrument and upon release of such light force by the user, the instrument will remain in the newly adjusted position.
U.S. Pat. No. 5,201,325, McEwen et al., Apr. 13, 1993, discloses an apparatus useful in surgery for holding retractors and other surgical instrumentation in a number of different positions required by a surgeon for the performance of a surgical procedure, including advanced sensing and regulation of retraction pressures and position; and incorporating a force amplification method to drive a locking mechanism in the supporting structure that utilizes a constrained, substantially incompressible, flexible solid material to yield a mechanism that is suitable for clinical use.
The surgical arms designed for holding, positioning and supporting patient limbs during operation must handle very significant loads. For this purpose, these devices are endowed with pneumatic brakes that include mechanical force multiplication that makes their design and constructions quite complicated and expensive. Similar approaches used in the design of above pneumatic limb positioning and holding devices have been used in the design of a passive pneumatic camera holder, the Endex arm (Andronic Devices, 1994). The Endex arm uses a number of internally pressurized links and single axis pneumatic brakes to lock in position a camera holder at the site required by a laparoscopic surgeon. Computer Motion's AESOP (Automated Endoscopic System for Optimal Positioning) 3000 (Sackier, 1996) is an FDA-approved voice controlled active arm used for maneuvering and positioning an endoscopic camera for laparoscopy.
Another "general purpose" surgical holding arm that has been developed for holding endoscopic and orthopaedic tools is the "automatic, medical holding device" research arm described in Erbse et al., 1997. It is a passive arm with several links connected through ball joints at their ends. The ball joints are locked in place with piezoelectric actuators used as jams.